1. Field of the Invention
The present invention relates to a support member for large area glass substrates. More particularly, the invention relates to a support member for supporting large area glass substrates during high temperature processes.
2. Description of the Related Art
Thin film transistors have been made here to for on large glass substrates or plates for use in monitors, flat panel displays, solar cells, personal digital assistants (PDA), cell phones and the like. The transistors are made by sequential deposition of various films including amorphous silicon, both doped and undoped silicon oxides, silicon nitride and the like in vacuum chambers. Thin films for transistors can be deposited by chemical vapor deposition (CVD) for example. After deposition, many films used for transistor fabrication are subjected to heat processes.
CVD is a comparatively high temperature process requiring that substrates withstand temperatures on the order of 300° to 400° C. Higher temperature processes such as those above 500° C. are envisioned. CVD film processing has found wide spread use in the manufacture of integrated circuits on glass substrates. However, since glass is a dielectric material that is very brittle and is subject to warping or cracking when heated rapidly to high temperatures, care must be taken to adjust the rate of heating large areas of substrates to avoid thermal stress and resulting damage.
Systems exist currently to preheat glass substrates prior to processing and to conduct post processing heat treatment operations. Conventional heating chambers have either one or more heated shelves for heating one or a plurality of glass substrates. Glass is typically supported above a shelf on spacers to improve heat uniformity and throughput. To minimize costs, conventional spacers are typically formed from easily machined metals, such as, for example, stainless steel, aluminum, aluminum nitride, and the like. However, conventional spacers may tend to mare or otherwise damage the surface of the glass, possibly resulting in an imperfection in the glass surface. Later, during cleaving operations, the imperfections in the glass surface may result in abnormal cleaving operations causing loss of a device or breakage of a substrate.
In some cases, it is believed that portions of the spacer in contact with the glass may react with and temporarily bond to the glass. When these bonds are later broken, residues of the earlier reaction remain on the spacer potentially damaging the substrate being processed. In addition, the residue poses a risk of damage to substrates processed thereafter or may become a source of contamination within a heat treatment chamber. Moreover, the earlier residue may incite additional chemical reactions between the spacer and the glass or further degrade a spacer support surface or the lifetime of the spacer.
Therefore, there is a need for a glass support for high temperature glass-panel operations that reduces or eliminates glass damage.